The invention relates to a tunable active high-pass filter. More particularly, the present invention relates to tunable active high pass filter of the type including an amplifying element having resistors and capacitors connected in its positive feedback path with at least one of the resistors being adjustable.
Active filters, which can be balanced, and which contain an operational amplifier as the active amplifying element and utilize positive feedback, are conventional, see for example [Radio Review] 1978, issue 5, pp. 183 and 184. These filters are distinguished in that they make a strict distinction between pass-band and suppression band. However, ordinarily two adjustable resistors (tandem potentiometer) are required for tuning these conventional filters with operational amplifiers.